The present invention relates to a rotational joint assembly for a prosthetic leg and more particularly to a restrainer mechanism which applies a restraining force for limiting the rotation of an artificial foot during walking and for applying a restoring torque thereto.
In the normal function of the human leg during walking, there is a rotation of the foot in relation to the hips. Lack of this rotational capability in a prosthetic leg results in an awkward gait requiring excessive efforts during walking and thereby producing an uneven wear of shoes.
An example of a joint for allowing rotation of an artificial foot is disclosed in U.S. Pat. No. 3,842,443 granted on Oct. 22, 1974. In this particular device, joint segments are attached to respective sections of a prosthetic leg. A resilient sleeve is arranged about the joint segment for restoring same to a normal or predetermined relationship with respect to one another following the application of torsional forces to the joint. While this prior art device may operate satisfactorily for the purposes intended, there is no provision for limiting the degree of rotation of the foot during walking and for applying a restoring torque to the foot for returning it to its initial position.